POLYGONS

A polygon is a closed 2 - dimensional shape made of straight lines with 3 or more sides. Triangles and rectangles are polygons.

REGULAR POLYGONS

CHARACTERISTICS OF A REGULAR POLYGON* A CLOSED SIDED SHAPE*Has straight sides*All of the sides are equal*All of the angles are equalEXAMPLES:

These are all regular polygons

A 7 sided polygon

IRREGULAR POLYGONS

CHARACTERISTICS OF IRREGULAR POLYGONS* CLOSED SIDED SHAPE* Has straight sides* All side lengths may not be equal* All angles may not be equalEXAMPLE:

These are irregular pentagons - each shape has 5 sides but the lines and the angles do not have the same measurement.

A pentagon is a 5- sided polygon ( a flat shape with straight lines)

TRIANGLES

Triangles are polygons as well. They are a closed shape with 3 or more sides. There are regular and irregular polygons.> A triangle has three sides and three angles> The three angles always add to 180 degrees> There are three special names given to triangles that tell how many sides (or angles) are equalThere can be 3, 2 or no equal sides / angles:

EQUILATERAL TRIANGLE

> Three equal sides> Three equal angles, always 60 degrees

ISOSCELES TRIANGLE

>Two equal sides> Two equal angles

SCALENE TRIANGLE

> No equal sides> No equal angles

WHAT TYPE OF ANGLE?

Triangles can also have names that tell you what type of angleis inside:

ACUTE TRIANGLE

> All angles are less than 90 degrees

RIGHT TRIANGLE

> Has a right angle (90 degrees)

OBTUSE TRIANGLE

> Has an angle more than 90 degrees

COMBINING THE NAMES:

Sometimes a triangle will have two names, for example:

RIGHT ISOSCELES TRIANGLE

> Has a right angle (90 degrees), and also two equal anglesCan you guess what the equal angles are?